How is balancing a chemical reaction similar to taking inventory in a store?

The both must be balanced and every input must be accounted for at the output.

Explanation:

In taking inventory at the store, one must make sure that the total inventory is always balanced at the end of the inventory log (all stocks taking out must be accounted for in the end) so also is the chemical reaction in which the total reactants species atoms must equal the total product specie atoms.

a:

by the combination of an unlimited number of elements